code: def test_specifier_z_error(self):
      error_msg = re.compile("Invalid format specifier '.*z.*'")
      with self.assertRaisesRegex(ValueError, error_msg):
          f"{0:z+f}"  # wrong position
      with self.assertRaisesRegex(ValueError, error_msg):
          f"{0:fz}"  # wrong position
  
      error_msg = re.escape("Negative zero coercion (z) not allowed")
      with self.assertRaisesRegex(ValueError, error_msg):
          f"{0:zd}"  # can't apply to int presentation type
      with self.assertRaisesRegex(ValueError, error_msg):
          f"{'x':zs}"  # can't apply to string
  
      error_msg = re.escape("unsupported format character 'z'")
      with self.assertRaisesRegex(ValueError, error_msg):
          "%z.1f" % 0  # not allowed in old style string interpolation
      with self.assertRaisesRegex(ValueError, error_msg):
          b"%z.1f" % 0
  
imports: from test.support import verbose, TestFailed
  import locale
  import sys
  import re
  import test.support
  import unittest
label_desc: Use image node_id 18 for calling the FormatTest obj's underlying member method code with example usage: obj.test_specifier_z_error() without return types